SETUP:
PS3 and DVR running HDMI's to Receiver
Receiver running 40' 1.3 28AWG HDMI cable to Panasonic Ax200u projector
Receiver has upconversion turned off
Projector lamp mode set to "Normal" instead of "Eco Mode" (Eco mode caused a subtle brightness flicker issue)

ISSUE:
PINK FLICKER OCCURS ABOUT ONCE EVERY 1-2 HOURS.
ISSUE OCCURS WITH BOTH PS3 AND DVR (not a device issue)
ISSUE OCCURS BOTH IN ECO MODE AND NORMAL (not lamp 'setting' issue)

Has anyone come across this issue?

It's almost certainly a lamp issue. Mine went like that after about 500 hours. At 1500 hours I finally replaced the lamp and the problem went away.