Sex threw me into L&D at 39w 6d. I stayed there all night being monitored until they sent me home at 7am because the contractions were spacing out to 15-20 minutes. Baby girl arrived on her own time 3 days later.
This is probably the reason for half the triage patients I see. Don't feel bad. Most pregnant women don't drink enough water, then you add summer heat, and it's gonna happen a lot.