I'm not sure weather this was intended or not, but when using a 1.6.4 64x64 resource pack, the spacing on the characters is different.
To Replicate:
1. Download and install Faithful 64x64 for 1.6.4.
2. Run Minecraft in 14w07a
3. Look at any text.
MC-48669
64x64 Resource Pack character spacing is different.
Resolved
Invalid
0
Does this affect all 64x resource packs? If it doesn't it's likely just a problem with the pack.