That is expected behavior for annotation. Since you have zoomed your data frame out from the annotation's reference scale, the fonts should be smaller. If you zoom the data frame into 1:15,000, they will be huge. You can try overriding the symbology on the annotation layer's properties using the "Substitute individual symbols in the symbol collection" option. The creator of the annotation could disallow this however. Set the font size much larger until it looks right at that scale.
Another approach is to create a new annotation feature at the preferred scale. ArcCatalog has a place to do this on the feature class properties screen, but it requires exclusive access to the file and changes the file itself (it does not produce a new file). But you could copy your feature to a new feature name and run this tool. It does not work well for big changes in scale.