Knots will generally appear at every injection site. Hell, my glute still has a small but now painless knot from last wednesday!
Best thing to do is switch injection sites. Myself personally, I'm not too keen on bicep injections as they ruin my workout for the next few following days.
Wherever you may inject, it's probably a good idea to give the site a intense massage to prevent knots, swelling and pain related to injections.
Say for example you're injecting on a monday and working arms and chest on the tuesday. Injecting in the bicep I think is personally a waste as the knot you receive will limit your workout, hence, not gaining much strength as opposed to a glute injection.
I guess what i'm trying to say is, if you get knots and swelling on a regular basis as many of us do, don't inject where you're going to work out. Try hittin the glutes or tri's for a while.
Hope I've been some help...