PA28 with gear problem elected to return to departure airport; ATC declared emergency and issued go-around to parallel runway traffic; reporter may have crossed hold line.

Narrative

Landing gear would not fully retract. Asked Tower to let us do a low fly-by to right runway (Runway 30?) and check which gear(s) were not going up. They advised that left main was partially down. I then lowered the gear and asked if I could land. Clearance given to land; but Tower asked how many souls on board and fuel; and as I was landing; I saw the red lights of Crash Fire Rescue trucks rolling out. Landed without issues or incident (3 in the green) and taxied to ramp; but may have had a taxi incursion onto left (jet) runway; as Tower instructed another aircraft to cancel takeoff clearance due to an 'emergency.' I never declared an 'emergency' as none existed. Gear lowered normally and fully. ZZZ Fireman assisted in checking gear and we found hose clamp had moved out of position and was blocking full gear retraction on the left. I tightened hose back into position; finished preflight inspection and after clearances; taxied out and left to ZZZ1. I think with all the lights (fire trucks; ambulance; etc.) I was a little shaken and may have misunderstood Tower's hold short instructions.