OLV GPS 36 approach question

Went out seeking some IMC time today. Severe clear at my home airport,
so took a trip from KMBO (Madison MS) to KOLV (Olive Branch MS)

Early morning clouds at OLV was 500 overcast, so I figured by the time I
got there, it would at least be broken. It wasn't the clouds that was
restricting the visibility so much as the haze. 2 mile forward viz at
best on my final approach.

Memphis Approach asked what approach I wanted and I elected GPS RWY 36
approach. I was at 4000 feet and about 10 miles out I was cleared to the
NOCAP initial approach fix, My instructions were descend and maintain
2,100, cleared for the GPS36 approach. My heading was 006 to the fix so
it was as easy as it gets to to intercepting the final approach course.

When I was looking at the profile part, before NOCAP I was to maintain
2800. So rather then descend to 2100, I maintained 2800 til I got to
NOCAP.

I didn't say anything / question the approach controller since the
frequency was wall to wall traffic, but I didn't want to hit anything
poking out of the ground either.

What is the overriding factor in this case (besides my PIC decision of
maintaining 2800)?

I can see where the controller got the 2100 figure which was the final
approach fix step down altitude, but I also didn't want to cause a
traffic conflict by maintaining 2800. So, I figured I'd have a better
chance at 2800 then 2100 as things poking out of the ground won't move
out of my way.

Was I correct in maintaining 2800 before the IAF or is the controller
allowed to clear me below a minimum dictated by an approach chart?

Is a ASR in order or did I mess up somewhere?

Allen