how "new" are the gauges, and are they quality ones, or just basic aftermarket units ? there is a super wide range of quality out there today, so just because two gauges read the same, doesn't necessarily rule out anything. at 240*, an engine may not smell warm or be hard to restart. lots of new stuff run 215* thermostats, and run all day at 230* or so.
are there any other signs of high temperatures, such as pinging or paint discoloration ?
the right coolant mix, plus a good pressure cap, will prevent boil over [puking]up to 260*.