Thanks for the advice DRoy and for the original post.
When I got home from work yesterday, my Simcoe/Citra was still bubbling away. However, I was still a little upset with myself, so I decided to brew an AG Bitter. I used Brew365 to calculate the temp of my strike water, and, after adding the grains, I waited 15 minutes, checked the temp of the mash, only to find that I was off 2 degrees again (152 instead of 154). I added a little water, stirred and check the temp again. However, when I checked the temp, I, for some reason, grabbed a different thermometer. The second thermometer measured 154 degrees. Out of curiosity, I put my original thermometer in, and it still measured 152. My conclusion is that my original thermometer (which I used on my first batch) was the culprit.
After the initial addition of water, the mash stayed at 154 degrees the rest of the way. I think that my problem is now solved.
The rest of the second AG experience went pretty well. Although my hops additions were supposed to be at 60, 20 and 10, with irish moss at 15. However, when I put my irish moss in, I, inexplicably, grabbed my last hop addition, and put it in as well. I know that the 5 extra minutes probably won't affect the beer that much, but I am still very irritated that I made that mistake.
Oh well, I checked this morning and the bitter is bubbling away. Now, I just have to wait a month or so to taste the final product.
Thanks again DRoy for the advice and for the original post.
I'm glad you worked it out. I'm still relatively new to brewing, about 12 batches in, and I'll tell you, I do something wrong everytime. The degree of which varies, from screwed up hop schedules to dropping things in the cooled wort, but I almost never repeat the same error twice. It's all part of learning. Happy Brewing and let me know if you have any more questions!