Braxton hicks

I started having Braxton hicks at 19 weeks. I'm a first time mom so I worried this was way too early to be having multiple in an hour sometimes. I called the doctor, they didn't seem worried but said to watch them. Ended up taking a trip to Er. (Never again) and then finally my doctor office allowed me to come in for an internal ultrasound to make sure cervix is okay. My question is, did anyone else start having BH this early?! They don't hurt me. Just more freaky since everything goes rock hard! I'm 20 weeks tomorrow.