Some people have noticed that in version 4.6.62, text labels are quite small. The change was done based on a request to have the label size directly related to the label's 'height' attribute. So in that version, the label height was directly proportional to the 'height' attribute, in database units.
This is a bit small though (you may have wondered whether labels had actually disappeared), and other editors e.g. Virtuoso arbitrarily set a label with height 1.0 to be 1 micron high. So in version 4.6.63 labels will be set to an equivalent height. In the meantime a temporary workaround is to use the Display Options 'Label display scale factor' to set a scale factor for labels.
Labels in schematic/symbol views are handled differently and are scaled so they have a constant size, above a certain zoom threshold.