Look at it from a lender's point of view. If you have these open lines that have had low utilization forever, and suddenly they all shoot up, and you start making minimum or close to minimum payments, that tells a lender: This guy is in trouble, and it might be a good idea to limit my exposure to him. Ergo they lower the limit on your account with them.

If you have open lines that get utilized and paid regularly in large chunks, that tells a lender: "this guy spends a lot of money, and I can see that my competitor has offered him better terms that I did, so if I want his business, I need to get off my backside and make it worth his while, either by lowering his rate, giving him more credit or both.

You fall into that second category from what you have told us about your use habits, so IMO anyway, you have zero to worry about. You're the sort of customer that they fight over, not the sort they fight to get rid of.