You're OK; no harm, no foul. Pull it and watch. If she didn't conceive to the AI service, she'll probably be back in heat in a few days, you just delayed it a bit.
Several years ago, we had a group of 5 or 6 1st calf heifers that milked down pretty poor... didn't even bother trying to AI them, just turned 'em out to the bull. Was still in a 'building' mode, so we figured even if they didn't breed, we'd just bump them from the Spring herd to the Fall herd.
Preg check time... Open, open, open, open... last one coming through was so skinny that I said, "I'm not even gonna bother checking her - I KNOW she's open." Come fall, we synched 'em with GnRH/CIDR +PgF2; all the others cycled & bred, but not that one. I might have even hit her with another dose of prostaglandin before I kicked 'em out to the bull... come March, I looked out on the hill to see that (still kind of thin) brown cow with a fresh new calf. She was far enough along that prostaglandin injection alone wasn't enough to abort her.
I knew it then, know it now, but still often forget that the most common reason for a cow or heifer in dccent condition not cycling is...she's pregnant.