Am I running too slow?

I just finished my very first 4 mile run today.  I've never gone that far without walking in my life and I'm really proud of my accomplishment.  I averaged 10:49 per mile for the run.

About .5 mile from the end of my run I was struggling mentally to keep going and crossed paths with a woman going about the same speed as me in the same direction and asked if I could pace with her to try and finish.  As we ran I picked up my speed to match her and she told me that she does a 9.5' mile pace and that if I normally do 11' per mile yet can keep up with her at the end of my long run then I'm running too slow.

Is she right?  Should I be picking up the pace at the beginning of my runs or keep the same pace and run longer?  I should mention that in the last month not only have I been added distance but I've also knocked 40" off my average mile time.