Why would my 1SG make us take a PT test 30 days after the record?

As stated below, ask through your COC. When I took over as 1SG I ended up redoing the record APFT due to certain SPECIAL folks not following regulations and playing buddy games. As I wasn't there and my Commander didn't trust the results from the last record APFT we did another one, low and behold, a number of folks that were scoring really high either failed or didn't come close to the original scores. Between that and a practice of allowing off schedule APFTs as a work around you tend to track your get overs really easy. Take the APPT and try to score higher, all Soldiers should show gradual improvement or the PT program needs to be redone.

First and foremost... ask! As a promotable specialist, you should be inquiring your leadership on their particular technique, unit training plans, and troop leading procedures. You may find a simple explanation.
For yourself, you will soon join the ranks of the NCO Corps yourself, personal and professional development is important to your growth as a leader and Soldier. A PT test should never be avoided or feared. You should always maintain your fitness level and be ready to take a Record APFT, that is the professionalism and self-discipline required of today's leaders. Be resilient and adaptive to all situations. Lead by example, even at your level.
Do not complain, seek guidance and answers. Always remain the consummate professional, strengthen your character by seeking mentorship from your leaders. If you happen to find yourself in a situation in which the answers is "because I said so", remain the quiet professional and take it as lesson learned. Don't become the leader who was not engaged in Soldier development, know that there are good leaders out there who are engaged, lead by example, answers questions with well thought out processes and relevant professional development in mind.

Why not just ask him/her? The answer might serve as a leadership lesson...