If you reply with a "Sure" -- what is your problem?

Whenever someone replies "sure" -- no exclamation point! -- I feel like they're saying they're disinterested or pissed. For example:

Me: Wanna get a drink after work?

You: Sure

Me: Ready for our big trip?

You: Sure

Me: Running 5 mins late, hope that's OK

You: Sure

I literally hate when anyone responds with a "sure" -- no exclam! -- because it sends me into a spiral. It feels like they're saying they'll *do me a favor*. That's the vibe I get. And I hate it.