This condition is normal for special "high top" batteries. It is the same for all of the following batteries: 12N7D-3B, YB7C-A, YB9A-A, YB10A-A2, YB12C-A, YB14A-A1, YB14A-A2, YB16CL-B, YB30CL-B. All 9 of these battery types are what is referred to as "Spill Resistant". They all have 6 individual valves per cell. The red seal tube really does not hold the air in, the yellow filler cap does. These batteries are all used in applications where the battery could be exposed to a roll-over (ATV and PWC). You will notice that all 9 of these batteries have higher (taller) black covers than a standard battery. This is where the extra venting/valving is housed. The key to filling is allowing air to get in the filling hole, while filling the acid through the hole as well. If you try to seal the hole tight, and pour the acid, it will not go anywhere, because there is nowhere for the air to dissipate.