It marked the striker's first for the club since joining in January 2013.
Jordi Gomez's shot was heading off target but deflected in off the outstretched leg of Graham and he later said: "I'll take it!
"It's been a frustrating couple of years at the club, I'm delighted to get my first goal.
"It's put the pressure back on everyone else, I think it takes us up to 14th or something like that. Now we just need to focus on each game.
"The boys did well last year, we got a lot of belief from that. The momentum's there, we need to build on it this week."