findinghumility- great additional comments. It is true that if you're used to checking yourself regularly and know your cervical changes then you'd notice something was "off". And I agree that you won't feel the mucous plug. The cervix is usually "long".
I agree with both of the above posters...Great posts!
Yeah definitely don't stress unless you have some other reason to believe you are going to have early labor like painful contractions, bloody show, etc. I do cervix checks from time to time when I'm not pregnant as we use fertility awareness to avoid or achieve pregnancy and the cervix is one of the ways to know if you are close to ovulation etc. My point is I'm used to checking my cervix and I did check it once now that I'm pregnant just out of curiosity. like Joy said it was very high, very soft (probably what you are describing as "loose)etc. That's actually a normal sign of pregnancy. So if you aren't used to checking your cervix I'm sure it could have felt odd to you even if it's normal. Also to my knowledge your "mucus plug" isn't like it just sits down below your cervix where you would feel it if you checked. Your cervix is somewhat thick and the mucus plug fills in through out it sealing it off so to speak. That's why you normally have to start dilating and thinning before it comes out. Regardless I think you need to chill out and talk to your doctor at your next appointment unless you have some other reason to think you are dilating etc. Good luck!!
First, I wouldn't do self-checks. They're not reliable and when you're pregnant the cervix is usually so high you can hardly reach. I would mention it to the doctor, have them check it out at your next visit.