Very Responsible for you to be checking. If you are paying your credit card bills in full every month don't worry about it yet. I have always lived off of credit cards. I like the incentives they give me. Anyways, we too (my hubby and I) pay off our bills in full and that builds a great history.
Recently, if you read my bio, you know that our world fell apart and we are way in debt (morally that is... over 1 MIL $) Luckily I had so many credit cards.... we put a huge chunck of our debt on them and are going to have to pay them off that way. And because we had such a great history with them, many gave us 1.9% and 2.9% for the life of the loan!
So, keep up the good work and don't worry just yet. Trust me, I know my credit cards.... the rate they give you now doesn't mean a whole lot since they are never that great but if you keep a good record of paying your bills on time, a little over the minimum, or best all of it off, they will help you in the end because they won't want to lose you!