I have removed the cap several times on several of my ferementations. If you are careful, don't breath or sneeze in it, and don't slosh it around, I think you are fine. I haven't had an issue.
Also, I noticed that your next batch is High Country Canadian Draft. I made that for my first batch and would recommend the following:
1. Do not use the booster
2. Instead add in 1lb of Light Dry Malt Extract at the point of the instructions for booster
3. Use two cans of High Country Canadian Draft extract instead of one
4. Boil the wort after you have mixed in the HCCD HME for 15 minutes
5. With 5 minutes left in the boil, add a hop sack with 1/2 ounce of U.S. Saaz Pellet Hops in it.
6. Then pour it into the fermenter with the water as instructed and add to 8.5 quarts. Go ahead and keep the hops bag with Saaz in the fermenter.
7. Ferment for 21 days... (No peeking

)
8. After 21 days and assuming you have a bottling bucket by then (we all know by now that you can't resist ) mix into bucket with 5 packed and level Tablespoons of corn sugar boiled in 1/2 Cup of Water. Then bottle
9. Let carb for 3 weeks @ 70 degrees (no exceptions)
10. Let condition after that for 3 weeks.
Without too much more effort or cost, and 7 additional weeks of impatient waiting, you will have the some of the best Canadian Draft beer made at home that you could do. Good Luck, I hope you try it and like it. I think it is way better than the standard recipe. :rockin: