Hydrogen ions are small and so pass through RO membranes more easily that OH ions so there is a small shift in pH from the RO process itself but the main effect is that the buffering capacity (alkalinity) of RO water is small so that the small amount of CO2 which dissolves in it can shift its pH noticeably. But the buffering capacity is still very small and you do not need to worry about this shift. This 'acid' will be overwhelmed by the buffers in the malts.
pH strips are notorious for reading low though some are better than others. A brewer needs a thermometer, a hydrometer and a pH meter.
As for info for the technically inclined try www.wetnewf.org
. The 'Articles' tab has a few pages on some of the basics plus some of the newer things I've found out in researching some stuff for Palmer's upcoming water book. For more in depth treatment go to the 'PDFs' tab and check the two part article on Alkalinity. The Cerevesia article is a more formal, in depth, review of mash tun/water chemistry.