Expecting possible triplets!

Angie
We had our ultrasound today and saw 3 sacs at 6 wks 4 days.  Baby A and Baby C had heartbeats but the tech said Baby B was hard to reach and couldn't get to the heartbeat. She couldn't tell if it was a late bloomer or if it's just a sac.   I was curious if this had happened to anyone else and when they went back the baby was measuring ok?