Also, check the 1st full print before making extras as you might want to make changes (burning, dodging) since your test strip only covers part of the image. If you're judgeing your exposure based on the test strip increments, the final exposure can be different from the multiple 'shots' of light the test strip receives. I never used to see this with my Durst enlarger but I've been using a LPL thats powered by a transformer and I definetly have this effect. I do an extra (small section) test print at a time slightly less than the test print indicates to double check the exposure. Sometimes I'll do this on a full sheet of paper to check for dodging and burning requirements.

If you've still got some of the Ilford left, you could process some without exposure and preferably in the dark to make sure it's not off.