It comes despite the EIS-FELA issuing a joint statement with Colleges Scotland last week agreeing to suspend the action.
The GMB said its members had voted by almost 4-1 against a revised offer, and walked out on Friday for four days.
Members of the GMB will be on strike for the next four days.
The University and College Union said its members at 13 Scottish universities will take part in 14 days of strike action.
A new vote will be opened this week by the Educational Institute of Scotland (EIS).