4weeks ago gf took planb one step condom ripe.her period this week.today i fingered my gf n there was bleending could it be period or something else?

Could be period: If she has not bled in the past with this activity,unless this time it was more vigorous,most likely menses.

Irritation?: This could just be local irritation. Make sure your hands are clean and the fingernails are short! Does not sound like anything serious. After Plan B, the cycle may be a little irregular. If it persists, see a Provider.