Last fall when my pool water temperature was in the 80s my salt reading from the Pool Pilot confirmed with Aquachek salt test strips was 3,400.

My water temperature is now 55 degrees. The Pool Pilot is now reporting a salt reading of 2,800. I have not drained and replaced water. I still have my winter cover on the pool.

I can think of several possible explanations.
1 The Pool Pilot salt readings are affected by the water temperature & you should ignore the reading until the water temperature reaches a certain temperature.
2 The water has thermal layers or the salt levels can vary in the pool until the water circulates properly.
3 I need to clean the plates. (The plates were checked last fall & were in good shape.)

Suggestions?

The Pool Pilot salt sensor is temperature compensated. It doesn't perfectly correct for temperature variations, but it comes fairly close. Their salt sensor is also not affected by the condition of the plates, it is a completely separate sensor.

You don't want to do any water testing, salt level or anything else, until the pump has been running for several hours after first opening in the spring. It can take a while for everything to mix together again after being idle all winter. During the season testing should only be done after the pump has been running for 30 minutes or more.

I have had the pump running everyday for over one week. I have looked at my Pool Pilot salt reading only after the pump has been running for at least two hours.

Salt measurements are +-400 at best, so your two readings aren't all that different. Also, it is completely normal for salt levels to go down slowly over time (assuming you haven't added any salt). Some water is always splashed out, which lowers the salt level, and any backwashing you do will lower the salt level.