there's reason vs there's a reason

Some examples from the web:

• Only sometimes I hope it works out because there's reason to hope.
• So there's reason for your being confrontational?
• He's watched closely at work... ...and there's reason to believe that ADM has bugged his home.
• The drug seems to be working, and for the first time since we began treatment, there's reason to hope.
• There's reason to believe she's alive, being held in his compound.
• So if there's reason for doubt, Which there obviously is, Don't those families left behind
• Where are we? I will admit, on paper, there's reason for concern.
• He's the one that hurts you the most and there's reason to drop him.
• Priest, I don't think there's reason to fight.
• On this day, as harvest ends and winter approaches, there's reason to celebrate, as well as mourn.
• There are some other voices in the distance on the audio track, so there's reason to believe that it was in a public place.
• It's a government program designed to collect information about all Americans, not just people where they believe there's reason to think they've done anything wrong.
• And yet, speculative though the idea surely is, I aim to convince you that there's reason for taking it seriously, as it just might be right.
• Tripp, here's what I think we should do... I think we should let the police handle the matter, Let them decide whether or not there's reason for suspicion.
• There's reason to believe that a nerve agent will be developed and deployed.
• There's reason to believe that, had Langley's identity been kept confidential, his accomplice would already be in custody.
• There's reason to believe that she was murdered inside the container and locked in afterwards.
• There's reason to believe this valve leaches chemicals that cause platelet malfunction and massive strokes.
• There's reason to believe... the workers won't be able to resist much and it's expected...
• They all have the same virus, but they're different enough that there's reason to believe that they've been independently acquired.

Some examples from the web:

• Women don't go back to work that quick unless there's a reason.
• Thank you... there's a reason to question the findings.
• They say there's a reason for everything.
• Now there's a reason for it.
• He won't even admit there's a reason to.
• Donna, there's a reason I didn't tell you about her.
• Matt, there's a reason we haven't met.
• Matt, there's a reason we haven't met.
• Freud says there's a reason for everything.
• Usually, there's a reason.
• Mark my words, there's a reason Perez is gunning for me.
• I'm thinking there's a reason they're unexplored.
• I really hope there's a reason.
• You asked me if there's a reason I returned.
• Gaby, there's a reason I asked to see you.
• 'Cause there's a reason the churches are empty.
• 'Cause there's a reason the churches are empty.
• And there's a reason for that.
• I guarantee you there's a reason.
• No, there's a reason you're still here.