Can't find cause for two flats

[oz rider]

Does that mean I should pump my tires to a higher pressure? I usually keep the tires at the lower end of the range -- not for any particular reason.

Higher pressure (within the range) rolls easier, lower pressure is often more comfortable but harder pedalling and increases the risk of pinch flats. You can also get a pinch flat from hitting something - a rock, big stick, kerb hopping gone wrong etc.