If I ask for a credit increase on a store or gas credit card, is there any chance they could check my credit report and instead decide to cancel me or up my interest rate, etc?

Background -

This is a gas card from a national gas station chain and a department store card also from a national chain. My credit score WAS bad, I've been working on it and now it is "fair". I had these two cards from before it was bad...I didn't use them much while it was bad. The dept store one did lower my credit limit while I was having trouble but have since raised it back up (they just randomly did it - i didn't request). I've been REALLY good about paying on these cards for at least the last year and some, but I'm afraid that if I ask the gas card for an increase they might go the other way...

any advice or insight?

Yes store credit cards are pretty stingy with your CL

Hi, I certainly agree with you. Your advice is really very helpful for us.
Thanks a lot!